content: package com.alimert.passportreader.mlkit.camera;
  
  import android.annotation.SuppressLint;
  import android.content.Context;
  import android.content.res.Configuration;
  import android.util.AttributeSet;
  import android.util.Log;
  import android.view.SurfaceHolder;
  import android.view.SurfaceView;
  import android.view.ViewGroup;
  
  import com.alimert.passportreader.mlkit.other.GraphicOverlay;
  import com.google.android.gms.common.images.Size;
  
  import java.io.IOException;
  
  /** Preview the camera image in the screen. */
  public class CameraSourcePreview extends ViewGroup {
      private static final String TAG = "MIDemoApp:Preview";
  
      private Context context;
      private SurfaceView surfaceView;
      private boolean startRequested;
      private boolean surfaceAvailable;
      private CameraSource cameraSource;
  
      private GraphicOverlay overlay;
  
      public CameraSourcePreview(Context context, AttributeSet attrs) {
          super(context, attrs);
          this.context = context;
          startRequested = false;
          surfaceAvailable = false;
  
          surfaceView = new SurfaceView(context);
          surfaceView.getHolder().addCallback(new SurfaceCallback());
          addView(surfaceView);
      }
  
      public void start(CameraSource cameraSource) throws IOException {
          if (cameraSource == null) {
              stop();
          }
  
          this.cameraSource = cameraSource;
  
          if (this.cameraSource != null) {
              startRequested = true;
              startIfReady();
          }
      }
  
      public void start(CameraSource cameraSource, GraphicOverlay overlay) throws IOException {
          this.overlay = overlay;
          start(cameraSource);
      }
  
      public void stop() {
          if (cameraSource != null) {
              cameraSource.stop();
          }
      }
  
      public void release() {
          if (cameraSource != null) {
              cameraSource.release();
              cameraSource = null;
          }
      }
  
      @SuppressLint("MissingPermission")
      private void startIfReady() throws IOException {
          if (startRequested && surfaceAvailable) {
              cameraSource.start(surfaceView.getHolder());
              if (overlay != null) {
                  Size size = cameraSource.getPreviewSize();
                  int min = Math.min(size.getWidth(), size.getHeight());
                  int max = Math.max(size.getWidth(), size.getHeight());
                  if (isPortraitMode()) {
                      // Swap width and height sizes when in portrait, since it will be rotated by
                      // 90 degrees
                      overlay.setCameraInfo(min, max, cameraSource.getCameraFacing());
                  } else {
                      overlay.setCameraInfo(max, min, cameraSource.getCameraFacing());
                  }
                  overlay.clear();
              }
              startRequested = false;
          }
      }
  
      private class SurfaceCallback implements SurfaceHolder.Callback {
          @Override
          public void surfaceCreated(SurfaceHolder surface) {
              surfaceAvailable = true;
              try {
                  startIfReady();
              } catch (IOException e) {
                  Log.e(TAG, "Could not start camera source.", e);
              }
          }
  
          @Override
          public void surfaceDestroyed(SurfaceHolder surface) {
              surfaceAvailable = false;
          }
  
          @Override
          public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
      }
  
      @Override
      protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
          int width = 320;
          int height = 240;
          if (cameraSource != null) {
              Size size = cameraSource.getPreviewSize();
              if (size != null) {
                  width = size.getWidth();
                  height = size.getHeight();
              }
          }
  
          // Swap width and height sizes when in portrait, since it will be rotated 90 degrees
          if (isPortraitMode()) {
              int tmp = width;
              width = height;
              height = tmp;
          }
  
          final int layoutWidth = right - left;
          final int layoutHeight = bottom - top;
  
          // Computes height and width for potentially doing fit width.
          int childWidth;
          int childHeight;
          int childXOffset = 0;
          int childYOffset = 0;
          float widthRatio = (float) layoutWidth / (float) width;
          float heightRatio = (float) layoutHeight / (float) height;
  
          // To fill the view with the camera preview, while also preserving the correct aspect ratio,
          // it is usually necessary to slightly oversize the child and to crop off portions along one
          // of the dimensions.  We scale up based on the dimension requiring the most correction, and
          // compute a crop offset for the other dimension.
          if (widthRatio > heightRatio) {
              childWidth = layoutWidth;
              childHeight = (int) ((float) height * widthRatio);
              childYOffset = (childHeight - layoutHeight) / 2;
          } else {
              childWidth = (int) ((float) width * heightRatio);
              childHeight = layoutHeight;
              childXOffset = (childWidth - layoutWidth) / 2;
          }
  
          for (int i = 0; i < getChildCount(); ++i) {
              // One dimension will be cropped.  We shift child over or up by this offset and adjust
              // the size to maintain the proper aspect ratio.
              getChildAt(i).layout(
                      -1 * childXOffset, -1 * childYOffset,
                      childWidth - childXOffset, childHeight - childYOffset);
          }
  
          try {
              startIfReady();
          } catch (IOException e) {
              Log.e(TAG, "Could not start camera source.", e);
          }
      }
  
      private boolean isPortraitMode() {
          int orientation = context.getResources().getConfiguration().orientation;
          if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
              return false;
          }
          if (orientation == Configuration.ORIENTATION_PORTRAIT) {
              return true;
          }
  
          Log.d(TAG, "isPortraitMode returning false by default");
          return false;
      }
  }
  
  